Microcatheter tip

ABSTRACT

The present invention is directed to a dilator having a stiffened shaft for use as part of an introducer sheath assembly. The dilator includes a stiffener tube and a tip of the dilator which extends distally to the dilator stiffener tube. The transition between the stiffener tube and the tip of the dilator is positioned such that when the dilator is positioned within the catheter sheath, the transition is also positioned within the catheter sheath. By positioning the transition between the stiffener tube of the dilator and the tip of the dilator inside the catheter sheath, the catheter sheath can provide strain relief subsequent to lateral movement of the tip of the dilator in a manner that can prevent kinking of the dilator tip at the transition between the stiffener tip and the tip of the dilator.

RELATED APPLICATION

This patent application is a divisional of now pending U.S. patentapplication Ser. No. 11/348,022, filed Feb. 6, 2006, entitledMICROCATHETER TIP, which is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to catheters. In more particular, thepresent invention relates to an introducer sheath assembly having areinforced dilator which minimizes kinking or bending of the dilatorshaft.

2. The Relevant Technology

Catheters play an important role in the treatment and care of patientsin modern medicine. In particular, catheters provide relativelyunobtrusive access to remote portions of a patient's body, allowingdesired procedures or treatments to be performed. A wide variety ofgeneralized and specialized catheters have been developed and refinedfor particular uses. For example, angioplasty catheters have beenadapted to provide a safe and effective conduit for the delivery of astent and/or balloon to a narrowing or blockage in a patient's artery orvein. Typically, catheters are placed in a desired position within apatient utilizing a guidewire. The guidewire is threaded to the desiredposition within the patient and then the catheter is threaded over theguidewire.

One problem associated with some guidewires is that they have a diameteror thickness which requires a relatively large access puncture into thevasculature of the patient. The relatively large access puncture canresult in damage to the artery or other patient tissue. Such damage canprolong the healing and/or bleeding time through the guidewire accesspoint. Micropuncture catheters have been developed to provide arelatively smaller access puncture into the vasculature of the patient.Micropuncture introducer sheath assemblies include an introducer sheathwhich allows larger diameter guidewires to be introduced into thevasculature of the patient through the smaller access opening.

Utilizing a micropuncture introducer sheath assembly typically involvesproviding a small bore access puncture utilizing a small gauge needle.The needle is utilized to create an initial access puncture into thepatient's vasculature. A small diameter guidewire is then threadedthrough the original puncture needle which has a smaller diameter thanthe guidewire which is to be utilized to guide the catheter to thedesired location within the patient's vasculature. In one example, aguidewire having an 0.018″ diameter is utilized.

Once the micropuncture guidewire is positioned within the patient'svasculature, the original access needle can be withdrawn from thepatient. An introducer sheath assembly is then threaded over themicropuncture guidewire. Typically, the catheter sheath has a somewhatresilient configuration which allows for desired operability insubsequent steps of the procedure. The dilator is positioned within thecatheter sheath to provide additional rigidity required to insert thecatheter sheath into the patient. Additionally, the dilator's taperedtip transitions from the guidewire's outer diameter to the diameter atthe distal end of the sheath. The dilator typically includes a resilientdilator shaft which is sufficiently stiff to allow for access into thepatient along the guidewire, but sufficiently resilient to preventunneeded damage to the patient. Once the introducer sheath assembly hasbeen introduced into the patient, the guidewire is withdrawn from thepatient and subsequently the dilator is also withdrawn from the patientleaving the catheter sheath in place. A subsequent and larger diameterguidewire can then be introduced through the introducer sheath withoutthe need to create a larger access puncture in the vasculature of thepatient. Once the larger diameter guidewire is inserted into thepatient, the catheter sheath can be withdrawn and the guidewire can bemanipulated as required for proper placement of the guidewire in thepatient's vasculature or within another position within the patient'sbody.

One problem that has been encountered with the use of such introducersheath assemblies relates to introducer sheath assemblies that include astiffener tube as part of the dilator. The transition between thestiffening tube and the tip of the dilator sometimes buckles or kinksduring the insertion of the introducer sheath assembly into the patient.This is typically due to the fact that the stiffening tube that ispositioned within the dilator has a greater rigidity and strength thanthe material from which the tip of the dilator is formed. As a result,multiple introducer sheath assemblies may need to be utilized during asingle insertion procedure to allow for completion of the procedure oncean initial dilator tip has failed. This can increase the time needed tocomplete the procedure, as well as cost due to the fact that multiplemicropuncture catheters are utilized during the course of the procedure.A number of different approaches have been developed to attempt tostrengthen dilators and dilator tips, however, such attempts can oftenbe overly costly or fail to provide the desired properties to compensatefor failure of such dilator tips.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a dilator having a stiffened shaftfor use as part of an introducer sheath assembly. The dilator istypically utilized within a catheter sheath which is to be inserted intoa patient. The catheter sheath typically comprises a somewhat resilienttubular member which can be difficult to insert into the patient. Thedilator provides additional rigidity to allow for insertion of thecatheter sheath into the vasculature or body cavity of a patient. Thedilator can include a stiffener which extends from the proximal end ofthe dilator to the distal end of the dilator. A tip of the dilatorextends distally to the dilator stiffener. The dilator tip has anincreased degree of flexibility and/or resilience, which allows forinsertion of the tip of the dilator into the patient in a manner thatdoes not result in damage or unnecessary tearing of the patient'stissue.

According to one embodiment of the present invention, the transitionbetween the stiffener and the tip of the dilator is positioned such thatwhen the dilator is positioned within the catheter sheath, thetransition is also positioned within the catheter sheath. In otherwords, a portion of the tip of the dilator is positioned inside thecatheter sheath and a portion of the tip of the dilator is positionedoutside the tip of the catheter sheath. By positioning the transitionbetween the stiffener of the dilator and the tip of the dilator insidethe catheter sheath, the catheter sheath can provide strain reliefsubsequent to lateral movement of the tip of the dilator in a mannerthat can reduce or prevent kinking of the dilator tip at the transitionbetween the stiffener tip and the tip of the dilator. According to oneembodiment of the present invention, the tip of the dilator is longerthan traditional dilator tips allowing for positioning of the transitionfurther back relative to the catheter sheath than known introducersheath assemblies. In another embodiment, the catheter sheath is longerthan traditional catheter sheaths such that the tip of the cathetersheath is positioned distally to the transition between the tip of thecatheter and the catheter stiffener.

According to one embodiment of the present invention, the tip of thedilator is formed from a sleeve which is external to the stiffener tubeand runs along the length of the stiffener tube. The sleeve extends anamount beyond the distal end of the stiffener providing a tip at thedistal end of the dilator. According to one embodiment of the presentinvention, the tip of the dilator includes a flow back region which isin contact with the tip of the stiffener when a force is exerted againstthe end of the dilator tip. In this manner, contact surfaces areprovided between the stiffener and the dilator tip providing additionalstrength to the tip portion of the sleeve in a manner that minimizesbuckling of the sleeve.

According to one embodiment of the present invention, the dilator ismanufactured by positioning the sleeve over the stiffener tube. Amandrel is positioned within the stiffener up to the distal end of thedilator, including the portion of the dilator corresponding with the tipportion of the sleeve. A die is also positioned along the length of thedilator adjacent the sleeve and/or the stiffener tube. A radio frequencyor other heat source medium flows through the mandrel and die and isexerted on the sleeve and stiffener tube. Heating of the sleeve andstiffener tube forms the sleeve to the stiffening tube. Forming of thesleeve to the stiffening tube allows for proper operation of the dilatorduring the procedure for which the introducer sheath assembly is to beutilized.

During heating of the sleeve, the tip portion of the sleeve begins toflow back into the air gap region between the mandrel and the sleeveproximate the distal tip of the stiffener tube. This is largely due tothe fact that the mandrel is configured to have an outside diameterwhich approximates the inside diameter of the stiffener tube. The sleeveis configured to slide over the outside diameter of the stiffener tube.As a result, an air gap is formed between the inside diameter of thesleeve and the smaller diameter of the mandrel in the tip portion of thedilator that extends beyond the stiffener tube. Once the sleeve has beensufficiently heated such that flow back has been achieved into the gapbetween the tip of the sleeve and the mandrel, a contact surface isprovided on the tip of the sleeve against the forward facing surface ofthe stiffener tube. The mandrel and die can be removed subsequent toproper formation of the tip of the dilator.

According to one embodiment of the present invention, the dilator tipincludes both a flow back portion or other contact surface to interfacewith the stiffener tube and a transition between the stiffener tube andthe dilator tip which is positioned within the catheter sheath. Byproviding both a contact surface, a transition which can be positionedwithin the catheter sheath. Positioning of the transition in thecatheter sheath provides a stronger, more reliable, and kink-resistantcatheter tip.

These and other objects and features of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 is a perspective component view of an introducer sheath assembly,according to one embodiment of the present invention.

FIG. 2 is a perspective view of an introducer sheath assembly which hasbeen assembled for use in a procedure.

FIG. 3 is a close-up cross-sectional view of the tip of the introducersheath assembly illustrating the juxtaposition of the stiffener tube,transition, sleeve, and catheter sheath, according to one embodiment ofthe present invention.

FIG. 4 is a perspective view of an introducer sheath assemblyillustrating the positioning of the sleeve relative to the stiffenertube during manufacture of the dilator.

FIG. 5 is a perspective view of the mandrel and die assembly for usewith the stiffener tube and sheath prior to flow back of the sheathduring manufacture of the dilator.

FIG. 6 is a perspective view of the mandrel and die assembly subsequentto flow back of the sheath of the dilator tip during manufacture of thedilator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a dilator having a stiffened shaftfor use as part of an introducer sheath assembly. The dilator istypically utilized within a catheter sheath which is to be inserted intoa patient. The catheter sheath typically comprises a somewhat resilienttubular member which can be difficult to insert into the patient. Thestiffened dilator provides additional rigidity to allow for insertion ofthe catheter sheath into the vasculature or body cavity of a patient.The stiffened dilator includes a stiffener which extends from theproximal end of the dilator shaft to the distal end of the dilator. Atip of the dilator extends distally to the stiffener tube. The dilatortip has an increased degree of flexibility and/or resilience, whichallows for insertion of the tip of the dilator into the patient in amanner that does not result in damage or unnecessary tearing of thepatient's tissue.

According to one embodiment of the present invention, the transitionbetween the stiffener and the tip of the dilator is positioned such thatwhen the dilator is positioned within the catheter sheath, thetransition is also positioned within the catheter sheath. In otherwords, a portion of the tip of the dilator is positioned inside thecatheter sheath and a portion of the tip of the dilator is positionedoutside the tip of the catheter sheath. By positioning the transitionbetween the stiffener tube of the dilator and the tip of the dilatorinside the catheter sheath, the catheter sheath can provide strainrelief subsequent to lateral movement of the tip of the dilator in amanner that can prevent kinking of the dilator tip at the transitionbetween the stiffener tube and the tip of the dilator. According to oneembodiment of the present invention, the tip of the dilator is longerthan traditional dilator tips allowing for positioning of the transitionfurther back relative to the catheter sheath than known introducersheath assemblies. In another embodiment, the catheter sheath is longerthan traditional catheter sheaths such that the tip of the cathetersheath is positioned distally to the transition between the tip of thecatheter and the catheter stiffener.

According to one embodiment of the present invention, the tip of thedilator is formed from a sleeve which is external to the stiffener tubeand runs along the length of the stiffener tube. The sleeve extends anamount beyond the distal end of the stiffener tube providing a tip atthe distal end of the dilator. According to one embodiment of thepresent invention, the tip of the catheter includes a flow back regionwhich is in contact with the tip of the stiffener tube when a force isexerted against the end of the dilator tip. In this manner, contactsurfaces are provided between the stiffener tube and the dilator tipproviding additional strength to the tip portion of the sleeve in amanner that minimizes buckling of the sleeve.

According to one embodiment of the present invention, the dilator ismanufactured by positioning the sleeve over the stiffener tube. Amandrel is positioned within the length of the stiffener tube up to thedistal end of the dilator, including the portion of the dilatorcorresponding with the tip portion of the sleeve. A die is alsopositioned along the length of the dilator adjacent the sleeve and/orthe stiffener tube. A radio frequency or other heat source medium flowsthrough the mandrel and die and is exerted on the sleeve and stiffenertube. Heating of the sleeve and stiffener tube forms the sleeve to thedilator tube. Forming of the sleeve to the dilator allows for properoperation of the dilator during the procedure for which the introducersheath assembly is to be utilized.

During heating of the sleeve, the tip portion of the sleeve begins toflow back into the air gap region between the mandrel and the sleeveproximate the distal tip of the stiffener tube. This is largely due tothe fact that the mandrel is configured to have an outside diameterwhich approximates the inside diameter of the stiffener tube. The sleeveis configured to slide over the outside diameter of the stiffener tube.As a result, an air gap is formed between the inside diameter of thesleeve and the smaller diameter of the mandrel in the tip portion of thedilator that extends beyond the stiffener tube. Once the sleeve has beensufficiently heated such that flow back has been achieved into the gapbetween the tip of the sleeve and the mandrel, a contact surface isprovided on the tip of the sleeve against the forward facing surface ofthe stiffener tube. The mandrel and die can be removed subsequent toproper formation of the tip of the dilator.

According to one embodiment of the present invention, the dilator tipincludes both a flow back portion or other contact surface to interfacewith the stiffener tube and a transition between the stiffener tube andthe dilator tip which is positioned within the catheter sheath. Byproviding both a contact surface, a transition which can be positionedwithin the catheter sheath. Positioning of the transition in thecatheter sheath provides a stronger, more reliable, and kink-resistantdilator tip.

FIG. 1 is a perspective view of an introducer sheath assembly 10,according to one embodiment of the present invention. Introducer sheathassembly 10 is utilized to facilitate the introduction of a guidewire orcatheter into the vasculature or other body cavity of a patient.Micropuncture catheters have been developed to provide a relativelysmaller access puncture into the vasculature of the patient.Micropuncture introducer sheath assemblies include an introducer sheathwhich allows larger diameter guidewires to be introduced into thevasculature of the patient through the smaller access opening.

During a procedure, micropuncture introducer sheath assembly 10 isutilized to provide a small bore access puncture utilizing a small gaugeneedle (for example a 21 gauge needle). The needle is utilized to createan initial access puncture into the patient's vasculature. A smalldiameter guidewire is then threaded through the small gauge punctureneedle. The small diameter guidewire has a smaller diameter than theguidewire which is to be utilized to guide the catheter to the desiredlocation within the patient's vasculature. In one example, a guidewirehaving an 0.018″ diameter is utilized.

Once the guidewire is positioned within the patient's vasculature, theoriginal access needle can be withdrawn from the patient. An introducersheath assembly is then threaded over the micropuncture guidewire. Theintroducer sheath assembly can include a stiffening dilator which ispositioned inside a catheter sheath (also sometimes referred to as anintroducer). Typically, the catheter sheath has a somewhat resilientconfiguration which allows for desired operability in subsequent stepsof the procedure. The resilient nature of the catheter sheath can makeit difficult to introduce the catheter sheath into the vasculature ofthe patient without a stiffening dilator. The dilator is positionedwithin the catheter sheath to provide additional rigidity required toinsert the catheter sheath into the patient. A stiffened dilatortypically includes a stiffening tube along the length of the dilator anda somewhat more resilient dilator tip which is sufficiently stiff toallow for access into the patient along the guidewire, but sufficientlyresilient to prevent unneeded damage to the patient.

Once the introducer sheath assembly has been introduced into thepatient, the guidewire is withdrawn from the patient and subsequentlythe dilator is also withdrawn from the patient leaving the cathetersheath in place. A subsequent and larger diameter guidewire can then beintroduced through the introducer sheath without the need to create alarger access puncture in the vasculature of the patient. Once thelarger diameter guidewire is inserted into the patient, the cathetersheath can be withdrawn and the guidewire can be manipulated as requiredfor proper placement of the guidewire in the patient's vasculature orwithin another position within the patient's body.

In the illustrated embodiment, introducer sheath assembly 10 comprises acatheter sheath 12, a dilator 14, and a guidewire 16. During a procedurein which introducer sheath assembly 10 is utilized, catheter sheath 12and dilator 14 will typically be coupled together allowing theintroducer sheath assembly 10 to be threaded into the patient. Dilator14 is inserted along the length of catheter sheath 12 to providerigidity and stiffness to facilitate the insertion of catheter sheath 12into the patient. To insert catheter sheath 12 and dilator 14 into thepatient, guidewire 16 is first inserted into the desired position withinthe patient through an access needle which has been inserted through theskin of the patient and into a vein, artery, or body cavity. Onceguidewire 16 has been threaded through the access needle and into thepatient, the needle can be withdrawn leaving guidewire 16 in placewithin the patient.

The relatively small diameter of the components of a micropunctureintroducer sheath assembly 10 allow for a relatively small accesspuncture into the patient. For example, typically the access needleutilized with guidewire 16 can be a 21 gauge access needle or smaller.This allows a smaller guidewire 16 to be utilized. For example,guidewire 16 can be a 0.018″ guidewire or smaller. By utilizing suchsmall access needles and guidewires with introducer sheath assembly 10,the original access puncture to the patient's skin, body cavity, orvasculature is quite small. The small access puncture facilitates ashorter recovery time, less trauma to the patient, and whileabbreviating the length of bleeding from the access puncture and/or thevasculature of the patient.

Once guidewire 16 is positioned in the desired location within thepatient, dilator 14 is threaded over guidewire 16. As previouslydiscussed, dilator 14 is positioned within catheter sheath 12 such thatwhen guidewire 16 is threaded along the length of dilator 14, guidewire16 is also threaded along the length of catheter sheath 12. Dilator 14and catheter sheath 12 are then advanced along the length of guidewire16 through the access puncture in the patient's skin and into thedesired position within the patient's body. The configuration of the tipof catheter sheath 12 and dilator 14 result in little tearing or traumaat the access puncture. Instead, catheter sheath 12 and dilator 14results in stretching of the access puncture in a manner such that thesize of the access puncture quickly returns to the original puncturesize allowing for quicker healing at the access puncture site. Oncedilator 14 and catheter sheath 12 have been inserted into the patient,guidewire 16 is withdrawn from the patient. Subsequently, dilator 14will be withdrawn from the catheter sheath 12 allowing for thepractitioner to access the body cavity or vasculature of the patientthrough catheter sheath 12.

In one embodiment, a larger diameter guidewire can be threaded throughcatheter sheath 12 and into the vasculature of the patient withoutrequiring a larger access puncture typically required when a largerguidewire is inserted directly through an access needle. For example,such larger diameter guidewires can be a 0.038″ diameter guidewire whichrequires an approximately 0.040″ diameter puncture needle to be insertedinto the patient. Utilizing a 0.040″ diameter puncture needle instead ofthe exemplary 21 gauge needle which is utilized in connection withcatheter sheath 12 results in an access puncture that can be more thattwice the size of the puncture required when utilizing introducer sheathassembly 10.

In the illustrated embodiment, catheter sheath 12 comprises a sheath hub18 and a sheath tube 19. Sheath tube 19 is coupled to sheath hub 18 in amanner that allows for desired operation of sheath tube 19 relative tosheath hub 18. Additionally, sheath tube 19 is in fluid communicationwith sheath hub 18 allowing access to sheath tube 19 along the length ofsheath hub 18.

In the illustrated embodiment, sheath hub 18 comprises wings 20 a, b anda lower coupler 22. Wings 20 a, b facilitates manipulation of cathetersheath 12 and introducer sheath assembly 10 by providing a grippingpoint for the practitioner during utilization of the introducer sheathassembly 10. Lower coupler 22 is positioned at the proximal end ofcatheter sheath 12. Lower coupler 22 allows for coupling of the dilator14 to the catheter sheath 12 during operation of the introducer sheathassembly.

Sheath tube 19 includes a sheath tip 23 positioned at the distal end ofthe sheath tube 19. Sheath tip 23 is slightly tapered allowing forinsertion of the catheter sheath into the access puncture. Sheath tube19 typically has a resilient and somewhat flexible configurationallowing for introduction of larger diameter guidewires along the lengthof catheter sheath 12. The resilient nature of sheath tube 19 alsopermits expansion of the access puncture in the patient's skin whileprotecting the patient from damage as the guidewire is inserted.

Dilator 14 comprises a dilator hub 24 and a stiffener tube 32. Stiffenertube 32 provides additional rigidity and strength to dilator sleeve 34as introducer sheath assembly 10 is inserted into the patient. Dilatorhub 24 allows for manipulation of stiffener tube 32 while also allowingfor coupling of the dilator 14 to the catheter sheath 12 duringutilization of the introducer sheath assembly 10. In the illustratedembodiment, dilator hub 24 comprises a lower coupler 26 and grippingmembers 28. Lower coupler 26 is positioned on the distal side of dilatorhub 24 allowing for mating engagement of dilator hub 24 and sheath hub18. Gripping members 28 are positioned on the outside diameter ofdilator hub 24 allowing for gripping of the dilator hub 24 by thepractitioner. By gripping the dilator hub 24, the practitioner canmanipulate the dilator 14 to secure the dilator hub 24 to the sheath hub18. Additionally, gripping members 28 of dilator hub 24 allow thepractitioner to manipulate the introducer sheath assembly 10 during thecourse of the procedure.

Dilator sleeve 34 includes a dilator tip 27. Dilator tip 27 comprises asomewhat resilient member which is configured to prevent damage to thepatient tissue as introducer sheath assembly 10 is threaded along thelength of guidewire 16 and into the patient. Dilator tip 27 is somewhatmore resilient and deformable than stiffener tube 32. This is due to thefact that the stiffener tube 32 is positioned within dilator sleeve 34but does not extend into dilator tip 27.

Transition 29 represents the point at which the stiffener tubeterminates and dilator tip 27 begins. In the illustrated embodiment,transition 29 is positioned at a point that is more proximal thantraditional transition points on stiffened micropuncture catheters. Thisallows for transition 29 to be positioned proximally to the sheath tip23 of catheter sheath 12 when dilator 14 is threaded along the length ofcatheter sheath 12 and dilator hub 24 is coupled to sheath hub 18.Additionally, dilator tip 27 has a greater length from transition 29 tothe distal tip of dilator tip 27. The greater length of dilator tip 27allows a portion of dilator tip 27 to be positioned proximally to sheathtip 23 and within the catheter sheath 12. Additionally, a portion ofdilator tip 27 can be positioned outside of catheter sheath 12 anddistally to sheath tip 23.

The positioning of transition 29 within catheter sheath 12 allowscatheter sheath 12 to provide strain relief to dilator tip 27 subsequentto lateral movement of the dilator tip 27. Positioning transition 29within catheter sheath 12 relieves the strain that would normally becarried primarily at transition 29. Such strain is caused due to thestiffer configuration of dilator sleeve 34, which is co-extensive withthe stiffener tube 32, and the more flexible nature of dilator tip 27.By providing strain relief subsequent to lateral movement of dilator tip27, potentially damaging forces at transition 29 are dissipated. Bydissipating such forces, kinking, buckling, or bending of catheter tip27 at transition 29 is minimized in a manner that could result in thefailure of dilator tip 27 during the procedure. In other words,minimizing the potential for damage at transition 29 provides forcontinued integrity of dilator 14 during the course of an insertionprocedure.

As will be appreciated by those skilled in the art, a variety of typesand configurations of introducer sheath assemblies can be utilizedwithout departing from the scope or spirit of the present invention. Forexample, in one embodiment, the transition point is positioned at atraditional location along the length of the dilator. An elongatecatheter sheath is provided such that the sheath tip is positioneddistally to the transition. In another embodiment, a standard sizedcatheter sheath is utilized with a dilator having a shorter stiffener.An elongated dilator tip is provided such that the transition is movedproximally behind the tip of the catheter sheath. In yet anotherembodiment, a combination of an elongated catheter sheath, an elongateddilator tip, and a proximally positioned transition is utilized toprovide a strengthened dilator tip. In yet another embodiment, thedilator hub is secured to the sheath hub utilizing other than a lowercoupling. In yet another embodiment, a single hub is provided instead oftwo hubs.

With reference now to FIGS. 2 and 3, FIG. 2 is a perspective view of anintroducer sheath assembly according to one embodiment of the presentinvention. In the illustrated embodiment, dilator 14 is threaded alongthe length of catheter sheath 12. Dilator hub 24 is secured to sheathhub 18 such that catheter sheath 12 and dilator 14 operate as a singleinsertion instrument in cooperation with a guidewire 16 (see FIG. 2). Aspreviously discussed, a practitioner grasps one or both of sheath hub 18and dilator hub 24 to guide dilator tip 27 over the guidewire 16 andinto the insertion point as desired during the procedure.

In the illustrated embodiment, a cross-sectional view is taken alonglines 3-3 of FIG. 2 and is depicted in FIG. 3. FIG. 3 illustrates thejuxtaposition of sheath tip 23 relative to dilator tip 27 at transition29. Transition 29 is positioned proximally to sheath tip 23 such thattransition 29 is positioned within catheter sheath 12. Dilator tip 27extends from transition 29 to the distal end of dilator 14.

Dilator tip 27 has an elongated configuration such that a portion ofdilator tip 27 is positioned inside catheter sheath 12 and a portion ofdilator tip 27 is positioned outside of catheter sheath 12 andproximally to sheath tip 23. As dilator tip 27 contacts the patient'sskin or other patient tissue, a force is exerted against dilator tip 27.The force exerted against dilator tip 27 can result in lateral movementand/or lateral pressure on dilator tip 27. Such lateral movement andlateral pressure is typically conveyed along the length of the distalend of dilator 14 in a manner that can result in strain at transition29.

The configuration of the stiffener tube 32 and dilator tip 27 results instrain at transition 29. As a result, transition 29 can be a commonpoint of failure, such as buckling or kinking of dilator tip 27, duringthe insertion of the introducer sheath assembly into the patient.Catheter sheath 12 is configured such that interior walls of the sheathtip 23 contact the exterior walls of dilator tip 27. During lateralmovement of dilator tip 27, contact between dilator tip 27 and sheathtip 23 allows sheath tip 23 to provide strain relief along part, or all,of the length of dilator tip 27. By providing strain relief along thelength of dilator tip 27, sheath tip 23 minimizes the pressure ortorsion experienced at transition 29 in a manner which can substantiallyreduce the likelihood of failure at transition 29.

In the illustrated embodiment, dilator 14 comprises a stiffener tube 32and a sleeve 34. Stiffener tube 32 provides rigidity and strength todilator 14 that allows dilator 14 to facilitate introduction of cathetersheath 12 into the patient. In the illustrated embodiment, stiffenertube 32 comprises a flexible metal, hard plastic, or other materialwhich provides sufficient rigidity and strength to maintain theconfiguration of dilator 14. Sleeve 34 is positioned externally tostiffener tube 32. Sleeve 34 provides an outer coating to stiffener tube32 that facilitates sliding of dilator 14 along the length of cathetersheath 12 during insertion of dilator 14 into catheter sheath 12.Additionally, sleeve 34 comprises the material from which dilator tip 27is formed. The configuration of sleeve 34 allows for quick and efficientmanufacturing of dilator 14. For example, the configuration of sleeve 34allows for automation of the manufacturing process in a manner thatsubstantially minimizes the cost of manufacturing the dilator 14.

In the illustrated embodiment, a dilator inside diameter 40 isdetermined by the inside diameter of stiffener tube 32. The dilatoroutside diameter 42 is determined by the outside diameter of the sleeve34. Sleeve 34 is coupled to stiffener tube 32 at the stiffenertube/sleeve interface 36. In one embodiment of the present invention,sleeve 34 is ultrasonically welded to stiffener tube 32 at the stiffenertube/sleeve interface 36. In another embodiment, the sleeve is formed tothe stiffener tube/sleeve interface utilizing a heat source medium,adhesive, or other known chemical or mechanical forming processes.

As will be appreciated by those skilled in the art, a variety of typesand configurations of dilators can be utilized without departing fromthe scope and spirit of the present invention. According to oneembodiment of the present invention, a stiffened support member, orring, is provided within the introducer sheath located at the junctureof the stiffener tube and dilator tip, further reinforcing the joint.According to another embodiment, a solid support member is provided.According to another embodiment, a braided, woven, wrapped or othersupport member. According to another embodiment, a support member isformed having a co-extrusion or a portion having a co-extrusion.According to yet another embodiment, a support member is located withinthe dilator.

FIG. 4 is an illustrative view of stiffener tube 32 and sleeve 34 duringmanufacturing of dilator 14. In the illustrated embodiment, stiffenertube 32 has a substantially uniform cross-section. Sleeve 34 also has asubstantially uniform cross-section. The inside diameter of the sleeve34 is approximately the same as the outside diameter of the stiffenertube 32. In this manner, the sleeve 34 can be positioned over and alongthe length of the stiffener tube 32. As is illustrated in FIG. 4, thelength of sleeve 34 is somewhat longer than the length of stiffener tube32. The additional length of sleeve 34 allows the tip of sleeve 34 toextend beyond the stiffener tip 38. By positioning sleeve 34 over thestiffener tube 32, sleeve 34 does not directly contact the surface ofstiffener tip 38.

Because sleeve 34 does not directly contact the front surface ofstiffener tip 38, the transition from stiffener tube 32 to the tip ofsleeve 34 results in a potential point of buckling or kinking of sleeve34. This is largely due to the fact that the greater rigidity of thestiffener tube 32 and the somewhat more flexible and resilient nature ofthe sleeve 34 changes the overall characteristics of dilator 14 at theinterface corresponding with stiffener tip 38. In the event that lateralforces are exerted on the tip of sleeve 34, the portion of sleeve 34which is positioned distally to stiffener tip 38 can undergo somedeformation without resulting in buckling of the sleeve 34. However, dueto the increased strength and rigidity provided to dilator 14 bystiffener tube 32, the resilience of sleeve 34 begins to besubstantially limited at stiffener tip 38. The natural resilientdeformation of the portion of sleeve 34 positioned distally to stiffenertip 38 can result in buckling at the portion of the sleeve correspondingwith stiffener tip 38. As a result, instead of providing increasedstrength at the sleeve tip, stiffener tip 38 becomes a point of weaknessin the dilator which can result in failure of the tip of the sleeve. Aswill be appreciated by those skilled in the art, FIG. 4 represents astep in the manufacturing process and does not correspond with the finalconfiguration of the dilator or any resulting design implications of thecomponents shown in FIG. 4.

FIG. 5 is a perspective view of stiffener tube 32 and sleeve 34subsequent to positioning of a mandrel 44 and die 46 during manufactureof dilator 14. In the illustrated embodiment, a mandrel 44 has beeninserted along the length of stiffener tube 32 terminating at the distalend of sleeve 34. Similarly, die 46 has been inserted along the outsidediameter of sleeve 34 terminating at a point corresponding with thedistal end of sleeve 34. In the illustrated embodiment, mandrel 44 hasan outside diameter which corresponds with the inside diameter ofstiffener tube 32. Die 46 has an inside diameter which substantiallycorresponds with the outside diameter of sleeve 34. However, die 46 hasa somewhat tapered configuration at the portion of sleeve 34 positioneddistally to stiffener tip 38. The tapered configuration of die 46 allowsfor the creation of a taper in the tip of dilator 14 that facilitatesthe insertion of dilator 14 into the patient.

The tapered configuration of die 46 results in contact of sleeve 34 withthe distal portion of mandrel 44. However, due to the configuration ofstiffener tip 38 and the positioning of sleeve 34 along the length ofstiffener tube 32, an air gap 48 is created adjacent the portion ofmandrel 44 positioned directly distal to stiffener tip 38. As previouslydiscussed, air gap 48 can result in weakness at the stiffenertube/sleeve interface 36 due to the fact that sleeve 34 does not contactthe front surface of stiffener tip 38. Once mandrel 44 and die 46 havebeen positioned along the length of stiffener tube 32 and sleeve 34,heat is conveyed from mandrel 44 and die 46 to form sleeve 34 tostiffener tube 32. The heat conveyed by die 46 and mandrel 44 to theportion of sleeve 34 which is positioned distally to stiffener tip 38also results in deformation of sleeve 34. The deformation of the sleeve34 continues until the material of the tip of sleeve 34 begins to flowback into the air gap area 48 adjacent stiffener tip 38. This allows forthe material from which sleeve 34 is formed to fill the air gap 48 andprovide for a dilator tip having greater strength.

As will be appreciated by those skilled in the art, a variety of typesand configurations of mechanisms for forming stiffener tube to thesleeve can be utilized without departing from scope and spirit of thepresent invention. Additionally, a variety of types and configurationsof methods and apparatus can be utilized to create flow back orincreased material properties in the area of the stiffener tip withoutdeparting from the scope and spirit of the present invention. Forexample, in one embodiment, radio frequency heat is provided from themandrel and die to form the sleeve to the stiffener tube. In anotherembodiment, other thermal properties, mechanical forming, or chemicalprocesses are utilized to form the sleeve to the stiffener tube. In yetanother embodiment, forming of the sleeve to stiffener tube is providedin the absence of a mandrel and die configuration. In yet anotherembodiment, instead of providing flow back of the material from whichthe sleeve is formed to fill the air gap, a secondary member is formedto the sleeve in a manner that the tip of the dilator contacts thestiffener tip to provide for increased strength at the stiffener tip. Inanother embodiment, while a contact surface of the catheter tip isprovided, an air gap is positioned between the contact surface and thestiffener tip. When forces are exerted on the catheter tip, flexing ofthe sheath results in closing of the air gap and interaction between thecontact surface of the catheter tip and the stiffener tip in a mannerthat provides increased strength at the transition.

FIG. 6 is a cutaway cross-sectional view of the dilator 14 subsequent toheating of sleeve 34 to form sleeve 34 to stiffener tube 32.Additionally, FIG. 6 illustrates the portion of sleeve 34 positioneddistally to the stiffener tip 38 subsequent to flowback of the materialof sleeve 34 into air gap 48 (see FIG. 5.) In the illustratedembodiment, the shape of dilator tip 27 is formed subsequent to flowbackof the material from which sleeve 34 is formed.

The flowback of the sleeve material results in a configuration ofdilator tip 27 in which a contact surface is provided between dilatortip 27 and the front surface of stiffener tip 38. By providing a contactsurface between dilator tip 27 and the front surface of stiffener tip38, greater stability and strength is provided subsequent to forcesbeing exerted on the distal end of dilator tip 27. As a result, whenforces are exerted on dilator tip 27, the forces are conveyed directlyfrom dilator tip 27 to the stiffener tube 32. This minimizes excessivelateral movement that can result from forces which are exerted in aperpendicular vector relative to the front of dilator tip 27.Additionally, stiffener tube 32 can provide additional support andstrength to dilator tip 27 facilitating proper insertion of dilator tip27 into the patient. The combination of the contact surface forinteraction with stiffener tip 38 and the strain-relief propertiesprovided by interaction of the catheter sheath and the dilator tip 27,provides a catheter tip 27 having increased strength while alsoproviding resistance to kinking or failure of the catheter tip 27 attransition 29.

Subsequent to flowback of the material from which sleeve 34 is comprisedand the formation of dilator tip 27, die 46 and mandrel 44 are withdrawnfrom dilator 14. Dilator 14 can then be inserted into a catheter sheath,as illustrated in FIG. 3. Once the dilator 14 is inserted into thecatheter sheath 12, as illustrated in FIG. 3, the introducer sheathassembly 10 is ready to be inserted into the patient.

The flowback of the materials from which sleeve 34 is comprised and theconfiguration of dilator tip 27 provide for a substantially uniforminside diameter along the length of the dilator 14. By providing asubstantially uniform inside diameter, guidewires, other materials, orimplements can be introduced and withdrawn along the length of dilator14 without obstruction. In the illustrated embodiment, the insidediameter of dilator 14 substantially corresponds with both the insidediameter of the stiffener tube 32 and the outside diameter of themandrel 44.

By utilizing a mandrel and die configuration in connection with astiffener tube and sleeve, flow back of sleeve 34 can be effectuated toprovide a contact surface of the dilator tip for interaction with thefront surface of the stiffener tip. The dilator can be manufactured in aquick and efficient manner without requiring specialized machinery,components, materials, or properties other than the mandrel and dieconfiguration as depicted in reference to FIGS. 5 and 6. As a result,the system and method of manufacturing the dilator is bothstraightforward and cost-effective. As a result, a catheter tip isprovided having increased strength which can be manufactured in a costeffective manner.

As will be appreciated by those skilled in the art, a variety of typesand configurations of dilatore and systems and methods of manufacturingdilatore can be provided without departing from the scope and spirit ofthe present invention. For example, in one embodiment, additional stepsor processes are provided to create additional coatings or tapers of thedilator. In another embodiment, a die having a substantially conicalconfiguration is provided to create the taper of the dilator tip. Inanother embodiment, flowback of the material from which the sleeve isformed occurs in a step that is separate from forming of the sleeve tothe stiffener tube. In yet another embodiment, the material from whichthe sleeve is formed is separate from the material which is utilized toform all or part of the catheter tip.

What is claimed is:
 1. A method of accessing a vasculature or a bodycavity of a patient comprising: obtaining a first tubular membercomprising a proximal portion and a distal portion, wherein the proximalportion is stiffer than the distal portion, wherein the distal portioncomprises a taper adjacent a distal end of the distal portion, whereinthe taper comprises a proximal taper end and a distal taper end, whereinthe proximal taper end is disposed distally of the stiffer proximalportion, wherein the distal portion of the first tubular membercomprises a contact surface to abut a front surface of a proximalcomponent of the first tubular member, wherein the contact surface isdisposed substantially parallel to and in abutment with the frontsurface of the proximal component of the first tubular member to definea transition, and wherein the contact surface and the transition arespaced proximally of the proximal taper end; obtaining a second tubularmember having a distal end; inserting the first tubular member within alumen of the second tubular member such that the transition is disposedproximally of the distal end of the second tubular member, and such thatthe distal end of the second tubular member is disposed proximally ofthe proximal taper end of the first tubular member; and introducing thefirst tubular member and the second tubular member into a vasculature ora body cavity of a patient.
 2. The method of claim 1, furthercomprising: introducing a needle into the vasculature or the body cavityof the patient; inserting a first guidewire through a lumen of theneedle; withdrawing the needle; and introducing the first tubular memberand the second tubular member into the patient over the first guidewire.3. The method of claim 2, further comprising: withdrawing the firstguidewire from the patient; withdrawing the first tubular member fromthe patient; introducing a second guidewire into the patient through thelumen of the second tubular member; and withdrawing the second tubularmember from the patient.
 4. The method of claim 3, wherein the secondguidewire comprises a larger diameter than the first guidewire.
 5. Themethod of claim 1, further comprising: contacting a portion of aninterior wall of the second tubular member to a portion of an exteriorwall of the first tubular member at or adjacent the transition, suchthat strain relief is provided along at least a portion of the firsttubular member.
 6. The method of claim 1, further comprising: coupling aproximal end of the first tubular member to a proximal end of the secondtubular member.
 7. The method of claim 6, wherein coupling the firsttubular member to the second tubular member positions the proximalportion of the first tubular member, the distal portion of the firsttubular member, and the second tubular member to distribute lateralstress to reduce kinking of the first tubular member at or adjacent thedistal end of the second tubular member.
 8. The method of claim 7,wherein the coupling is configured to position the proximal end of thedistal portion of the first tubular member within the lumen of thesecond tubular member.
 9. A method of disposing a dilator in a sheathcomprising: inserting a dilator comprising a reinforced proximal portionand a less rigid distal portion into a lumen of a sheath, wherein theless rigid distal portion comprises a taper adjacent a distal end of thedistal portion, wherein the taper comprises a proximal taper end and adistal taper end, wherein the proximal taper end is disposed distally ofthe reinforced proximal portion, wherein the distal portion comprises acontact surface, wherein the contact surface is configured to abut afront surface of a proximal component of the dilator, the contactsurface and the front surface defining a transition, wherein the frontsurface is spaced proximally from the contact surface at the transition,and wherein the transition is spaced proximally of the proximal taperend; and coupling a proximal end of the dilator to a proximal end of thesheath such that the transition is positioned proximally to a distal endof the sheath and the proximal taper end of the dilator is positioneddistally to the distal end of the sheath.
 10. The method of claim 9,further comprising: engaging threads at the proximal end of the dilatorto threads at the proximal end of the sheath.
 11. The method of claim 9,further comprising: contacting a portion of an interior wall of thesheath to a portion of an exterior wall of the dilator at or adjacentthe transition such that strain relief is provided along at least aportion of the dilator.
 12. A method of relieving strain on a dilatorcomprising: obtaining a catheter sheath; obtaining a dilator comprising:a stiffer proximal portion comprising a proximal component defining afront surface at a distal end of the proximal portion, a less stiffdistal portion comprising a contact surface at a proximal end of thedistal portion, wherein the contact surface is disposed substantiallyparallel to and in abutment with the front surface to define atransition, and a taper adjacent a distal end of the distal portion,wherein the taper comprises a proximal taper end and a distal taper end;inserting the dilator into a lumen of the catheter sheath; and couplinga proximal end of the dilator to a proximal end of the catheter sheath,wherein a distal end of the dilator is positioned distally to a distalend of the catheter sheath, wherein the distal end of the cathetersheath is disposed proximally to the proximal taper end, wherein thetransition is positioned proximally to the distal end of the cathetersheath, and wherein the proximal taper end is positioned distally to thetransition.
 13. The method of claim 12, further comprising: contacting aportion of an interior wall of the catheter sheath to a portion of anexterior wall of the dilator at or adjacent the transition such thatstrain relief is provided along at least a portion of the dilator. 14.The method of claim 12, wherein the catheter sheath is configured torelieve strain to the distal portion of the dilator at a point distal tothe transition in response to lateral movement of the distal portion ofthe dilator to prevent lateral kinking of the distal portion of thedilator at or adjacent the transition.